1. Field of the Invention
The present invention relates an information communication system for use in a robot converting an information signal into an optical signal to enable communication between constituent parts of the robot.
2. Description of the Related Art
Conventionally, in manufacturing industries on down, manufacturing assembly and checking automated by industrial robots have progressed. In recent years, even in a business field dependent on human actions and human services up to this day, robotization which is conducted by an assistance robot, performing nursing help and assistance for human work and having different uses in comparison to the industrial robot, has been expected to be put into practice.
It is required for such a robot to mount a variety of sensors and acquire information relating to operations to control it for performing accurate operations. For example, for a robot operating in a house, office or public institute, namely, for a “robot coexistent with human being”, it becomes important not only to perform a mere mechanical operation but also to allow a user (side receiving service or operator) to intuitively recognize an operation condition of the robot visually and audibly. For instance, in work by which the user transfers articles to the robot, after transferring the articles manually to the gripping part of the robot, the user has to quickly recognize whether or not the robot surely grasps the articles when the user takes off the articles.
To transfer the articles from the gripping part of the robot, the robot needs a plurality of sensors, in response to each operation, for instance, sensors to operate the gripping part depending on the firmness and shape so as not to break the articles in gripping them. The sensors monitor the start and end of the operation, and a presentation mechanism is also required to notify the monitored condition to the user.
A large number of signal lines are provided to transmit sensor signals output form the sensors to a control unit and an interface, respectively. For example, if the gripping part is disposed at a tip of an arm having a joint, the signal lines are wired in order to be laid along with the inside and outside of the arm.
The case of the laying of the large number of signal lines makes the arm thick and requires that the arm becomes so strong to bear the increase in weight due to the signal lines. If it is structured that the arm has a joint to be bent or expanded, an arm operation, breaking prevention and the like have been taking into account, drawing the wiring of the signal lines becomes hard and its structure becomes complicated.
To solve such a problem, JP-A 2005-94744 (KOKAI) presents a control system planning to save lines by reducing the number of the signal lines connecting the main control device of the robot and each set of equipment.
This JP-A 2005-94744 (KOKAI) discloses a technique dividing a frequency band of a signal propagated on a single signal line into a plurality and assigns frequency bands different from one another to a plurality of sets of equipment to be connected to the signal lines. According to the technique, signals different in frequency band having been input to each set of the equipment, respectively, the control system can independently control each set of the equipment. To conduct such independent control, the robot needs many sensors to dispose at each constituent part. The robot has to draw the wiring connecting the sensors to the control unit (sensor signal processor).
In the aforementioned technique, dividing the frequency band of the signal on the single signal line into the plurality results in reducing the number of the signal lines; however, not a few number of the signal lines remain yet. Therefore, providing the sensors at the constituent parts disposed at the tip of the arm with a multiple-joint poses a problem on the technique in drawing the wiring in the same manner as the case before. Accordingly, the larger the number of the joints becomes, the heavier a load is put on the wiring for each drive, and the problem on disconnections or the like has to be taken into account. If the constituent parts having different functions for the arm are structured to be displaceable by detaching, connectors and the like should be disposed halfway the signal lines, and the problem on the attenuation of the sensor signals are produced.
Further, communications among the constituent parts with radio equipment not requiring signal lines mounted are possible approach. However, in the case of intending to make a large number of radio communications within a limited region, there is the possibility that accurate communications are not made because of crosstalk, interference or overlapping of high-frequencies depending on a circumstance and a situation in the use places, and the desired number of robots cannot be operated simultaneously sometimes. If the robots are those for the nursing help, moving places including medical institutes such as hospitals, in the case in which the robots become generation sources of electromagnetic waves, the control system has to make the robots not affect on medical equipment.